000 AXNT20 KNHC 081736 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1236 PM EST SUN JAN 8 2017 Tropical Weather Discussion for North America, Central America Gulf of Mexico, Caribbean Sea, northern sections of South America, and Atlantic Ocean to the African coast from the Equator to 32N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 1200 UTC surface analysis and satellite imagery through 1715 UTC. ...SPECIAL FEATURES... ATLC GALE WARNING... A cold front extends from 31N68W across the central Bahamas and central Cuba into the Caribbean Sea. A very strong high pressure center of 1043 mb follows the front, producing a very tight pressure gradient across the western Atlantic and Florida. The most recent scatterometer data provided observations of gale force winds behind the front, while a pair of altimeter passes indicated seas of 13-14 ft in association with these winds. Winds are forecast to diminish below gale force early this afternoon. Fresh to strong Northerly winds are expected behind the front during the next 24-48 hours. The front is forecast to reach a position from Bermuda to eastern Cuba later today. Winds will begin to gradually diminish across the waters E of north and central Florida Monday and Monday night as the strong high pressure center in the wake of the front moves toward the Carolinas into the western Atlantic. See latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02KNHC for more details. GULF OF MEXICO GALE WARNING... Strong pressure gradient across the SW Gulf of Mexico, associated with a 1040 mb high pressure over eastern Mexico near Tampico, continues to support minimal gale force winds S of 20N W of 95W, where seas are in the 13-18 ft range. Winds are forecast to diminish below gale force early this afternoon. See latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. CARIBBEAN GALE WARNING... The aforementioned cold front continues SW from central Cuba to the Gulf of Honduras. Fresh to strong northerly winds are noted in the wake of the front based on scatterometer and surface observations. The front is forecast to reach a position from Hispaniola to the coast of Nicaragua near 13N83W by Monday morning. Winds are forecast to further increase to minimal gale force across the Windward Passage, the waters between Jamaica and Haiti and beyond across the central Caribbean to near 15N78W by Monday morning. These conditions are expected to persist to at least Tuesday morning. See latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends from the African coast near 09N13W to 07N19W. The Intertropical Convergence Zone axis continues from 07N19W to 05N28W to the coast of South America near 02S43W. Scattered moderate to isolated strong convection is from 00N- 04N between 00W-13W. Isolated moderate convection is from 00N-05N between 24W-30W. ...DISCUSSION... GULF OF MEXICO... A very strong high pressure center of 1043 mb over the SE CONUS extends a ridge across Florida, the entire Gulf of Mexico and eastern Mexico, where a 1040 mb high pressure is also noted near Tampico. Under the influence of the ridge, fresh to strong northerly winds are observed across the Gulf region with the exception of gale force winds across the SW Gulf. See Special Features for details. Cold air stratocumulus clouds, parallel to the wind direction, covers most of the Gulf waters. Persisting low cloudiness are banked up along the eastern slopes of the Sierra Madre mountains. Outside of the gale area, winds are northerly 20-30 kt with seas of 13-14 ft. The high pressure will slide eastward through Thursday while weakening. Winds are forecast to diminish across the Gulf from W to E through Tuesday. Strong cold air advection is expected to continue for the next 24 hours. In the upper levels, a trough extends from northern Florida to the SW Gulf. Strong subsidence and implied dry airmass is over the entire Gulf. CARIBBEAN SEA... A cold front is over the Caribbean Sea and extends from central Cuba to the Gulf of Honduras. See Special Features for details. The front is generating scattered showers and isolated thunderstorm over the Gulf of Honduras. High pressure over the central Atlantic combined with the Colombian/Panamanian low supports fresh to strong trades across the south-central Caribbean. A recent scatterometer pass confirmed the presence of these winds and also indicated fresh to strong northerly winds in the lee of eastern Cuba. Moderate to locally fresh trade winds are noted elsewhere. An area of cloudiness with embedded showers is over the SW Caribbean affecting parts of Nicaragua and Costa Rica. A diffluent pattern aloft is helping to induce this convective activity. Shallow moisture embedded in the trade wind flow will continue to move across the basin producing isolated to scattered passing showers. In the upper levels, a ridge is over the E Caribbean with axis along 65W. SW flow, on the west side of the ridge, is advecting mid-upper level moisture from the EPAC across the western half of the Caribbean Sea. ...HISPANIOLA... Moisture is forecast to increase across the island tonight and Monday ahead of a cold front currently moving across eastern Cuba. As a result, expect increasing shower activity with the potential of a few thunderstorms and gusty winds. ATLANTIC OCEAN... A cold front is moving across the western Atlantic and stretches from 31N68W across the central Bahamas and central Cuba into the Caribbean Sea. See Special Features for details. Visible satellite imagery shows an impressive and very well defined 240 nm wide-band of cloudiness with embedded showers and scattered thunderstorms in association with this front. Cold air stratocumulus clouds are behind the frontal boundary. A 1029 mb high pressure is ahead of the front, over the central Atlantic near 35N42W and extends a ridge SW to near the Turks and Caicos Islands. Farther east, there is a low pressure of 1011 mb near 30N26W. A trough extends from the low center to near 20N30W. The low is forecast to move westward and open up into a trough in about 24-36 hours. The pressure gradient between the low and the high pressure is producing an area of fresh to strong northerly winds particularly N of 24N between the low and about 40W based on a recent ASCAT pass. Some shower and thunderstorm activity is noted on the NE quadrant of the low center. For additional information please visit http://www.hurricanes.gov/marine $$ GR